patch 8.2.1544: cannot translate messages in a Vim script

Problem:    Cannot translate messages in a Vim script.
Solution:   Add gettext().  Try it out for a few messages in the options
            window.
diff --git a/runtime/optwin.vim b/runtime/optwin.vim
index 5bb78cd..67601a8 100644
--- a/runtime/optwin.vim
+++ b/runtime/optwin.vim
@@ -1,7 +1,7 @@
 " These commands create the option window.
 "
 " Maintainer:	Bram Moolenaar <Bram@vim.org>
-" Last Change:	2020 Jun 10
+" Last Change:	2020 aug 30
 
 " If there already is an option window, jump to that one.
 let buf = bufnr('option-window')
@@ -145,13 +145,13 @@
 setlocal ts=15 tw=0 noro buftype=nofile
 
 " Insert help and a "set" command for each option.
-call append(0, '" Each "set" line shows the current value of an option (on the left).')
-call append(1, '" Hit <CR> on a "set" line to execute it.')
-call append(2, '"            A boolean option will be toggled.')
-call append(3, '"            For other options you can edit the value before hitting <CR>.')
-call append(4, '" Hit <CR> on a help line to open a help window on this option.')
-call append(5, '" Hit <CR> on an index line to jump there.')
-call append(6, '" Hit <Space> on a "set" line to refresh it.')
+call append(0, gettext('" Each "set" line shows the current value of an option (on the left).'))
+call append(1, gettext('" Hit <Enter> on a "set" line to execute it.'))
+call append(2, gettext('"            A boolean option will be toggled.'))
+call append(3, gettext('"            For other options you can edit the value before hitting <Enter>.'))
+call append(4, gettext('" Hit <Enter> on a help line to open a help window on this option.'))
+call append(5, gettext('" Hit <Enter> on an index line to jump there.'))
+call append(6, gettext('" Hit <Space> on a "set" line to refresh it.'))
 
 " These functions are called often below.  Keep them fast!